It is known that the practice of skiing both when one goes downhill as well as at the bottom, requires the use of poles in a variety of situations with variable intensity and frequency above all as a function of the particular type of activity being carried out. In particular, during skiing when one goes downhill the poles are used as assistance elements during the phases of the departure and thrust in maintaining the equilibrium and in applying the trajectory, and also when one goes uphill.
On the contrary, in sking at the bottom and also during the practice of walking in ski boots, the poles are used to complete the motion of the legs following typically the cadence in a synchronous manner. Both these situations involve stresses of different nature and intensity which are transmitted to the limbs which maneuver the poles. Specifically in sking when one goes downhill these stresses are typically short, of great intensity and relatively sporadic and irregular. On the contrary, in skiing at the bottom, the stresses result more prolonged and of lower intensity but with high frequency of repetition typically equal to the forward steps. In every case for activities which are carried out with substantial intensity and/or extension of the period of time and in a particular manner for professional athletes, these stresses are capable of favoring or determining pathological conditions of the articulations of the upper limbs, in particular the wrists and the elbows. For the purpose of obviating these drawbacks there have been already adopted for some time shock absorbing devices above all on the poles which are used for the practice of skiing on a road (ski roller) and on the poles being used for pedestrian excursions. These known devices consist essentially of a simple spiral spring which is placed internally and coaxially with the pole. These devices may be placed at the level of the handgrips, or the tips, but also in any other intermediate position of the pole.
In actual practice these devices have given unsatisfactory results and in some instances have produced the opposite result during use. The absence of damping in fact brings about a constant tension of muscles and tendonitis of the limbs in elastic bearing and favor the occurrence of troubles such, for instance in the tendonitis In addition, these devices are capable of increasing the total weight of the pole and also increase the final cost for the user. These devices have been partially eliminated with a shock absorbing device for poles and similar articles described in Italian patent application, No. VI95A000131, dated Aug. 3, 1995, filed in the name of the applicant as in the present application. This device provides similarly to the devices of known type the presence of two cylinders coaxial with the longitudinal axis of the structure to be dampened, one of the two cylinders being placed partially within the other, with the possibility of sliding with respect to the same in the presence of stresses which occur on the structure during use following the contact with the bearing surface and is characterized mainly by the fact that it utilizes an elastomer as the elastic means.
Both the device described hereinabove as well as other devices which have been proposed for the same purpose operate with a damping action only in one direction of motion, generally from the position of rest in the direction of compression so that the result is they are substantially rigid in the opposite direction. Consequently the return of the rest position of the elastic element following the removal of the load causes a dry recoil which for instance amounts to a nuisance also because of the noise being generated over prolonged use.